1. Field of the Invention
The present invention relates to outputting process black using an image outputting apparatus, and more particularly, to a method of adjusting a ratio of black in process black according to the attributes of an object to be printed during a printing operation and a driver thereof.
2. Description of the Related Art
An ink jet printer, which is one of general image outputting apparatuses, prints color images using four colors of ink, i.e., magenta, cyan, yellow, and black. However, such an ink jet printer is disadvantageous in that black ink spreads on a color region on the border between a black region and a color region. Therefore, the quality of the color region deteriorates and the border between the black and color regions is unclear, thereby lowering the quality of the overall image.
The reason why the black ink spreads over the color region is because black and color inks are different types. That is, black ink is evaporative colorant ink, but color ink is infiltrative colorant ink. To solve this problem, it is suggested that mono black be replaced with process black at the border between black and color regions, with respect to some pixels. Some black pixels adjacent to the border between the black and color regions are printed with process black, which is obtained by overlapping cyan, magenta, and yellow colors, while the other black pixels are printed with mono black. The process black is obtained by using ink of the same type for printing color regions, thereby minimizing spreading of black color on the border between black and color regions. Also, even if black ink spreads over a color region, the spreading of mono black ink over process black is not visually detected since the color region approximates black color.
FIG. 1 shows an example of a general user interface screen of an apparatus connected to a printer to control an output of the printer. Referring to FIG. 1, the user interface screen presents only an option of selecting whether process printing is to be used or not when printing target data, based on the type of the data, e.g., a text, a graphic, and an image. The process black printing in which a ratio of black is determined by a system is wholly applied to the data to be printed using the process printing.
FIG. 2 is a flowchart illustrating a conventional method of performing process black printing using a printer. Referring to FIG. 2, whether data is to be printed using process black is checked in operation 200.
If the data is not to be printed using the process black, mono black printing is performed on the print data using only black ink in operation 210.
If the print data is to be printed using the process black, a value of a mono black color determined by a system is converted into a value of process black color in operation 220. For instance, if the mono black value is 5, a magenta value M, a cyan value C, and a yellow value γ are set to 5, respectively, and then a mixture of these colors is output as process black.
The data is printed using the converted process black in operation 230.
However, this method is not recommended in that only an option of determining whether process black is used or not is presented in a user interface screen, i.e., a function of adjusting a ratio of black in the process black is not included in this method.